JPH0367354B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a thick film circuit manufacturing apparatus that can be used in radio receivers, television receivers, communication equipment measuring instruments, and the like. Conventional structure and its problems Traditionally, thick film circuits were generally produced by forming conductor paste, resistor paste, etc. into the desired shape on a substrate using the Surleen printing method, and then drying and baking. . However, since the screen printing method uses a mask pattern, it takes time to replace the mask pattern and to clean the mask pattern and the squeegee, making it unsuitable for small-lot production or when there are many product changes. In response, a method has been devised and proposed in which the paste is directly extruded from a nozzle without using a mask pattern, and the paste is drawn on a moving substrate. In this drawing method, in order to make the film thickness of drawn lines uniform, it is necessary to keep the distance between the discharge hole and the substrate constant even if the substrate is "warped" or "twisted". Therefore, the unevenness of the substrate surface is measured using measurement methods such as laser length measurement, ultrasonic length measurement, air micro length measurement, and capacitance length measurement, and the results are fed back to the drawing head that holds the drawing nozzle to perform this drawing. There is a measurement method in which the head is moved up and down so as to keep the distance between the discharge hole and the substrate constant. In addition, as shown in Fig. 1, a contact piece 3 is attached to the tip of the nozzle, and this contact piece 3 is brought into contact with the substrate 5, so that the distance between the discharge hole 2 and the substrate 5 is kept constant at the height h of the contact piece 3. Methods have also been devised to make this happen. However, in either method, even if the distance between the discharge hole and the substrate is kept constant, if the width l of the discharge hole 2 (shown in Figure 2) changes, the film thickness t also changes, as shown in Table 1. It was hot. This is because as the width l of the discharge hole 2 increases, the difference in paste flow velocity between the center and the ends of the discharge hole 2 increases, resulting in a thicker film at the center than at the ends. This was revealed by the inventor's research.

[Table] For this reason, if the width of the discharge hole was changed in order to change the line width of the thick film paste, the film thickness would also change, causing variations in electrical characteristics. It has also been proposed to keep the film thickness constant and change the line width by repeating drawing using a single nozzle, but this method has the drawback of slow drawing speed and lack of mass productivity. OBJECTS OF THE INVENTION It is an object of the present invention to provide a method for drawing a thick film circuit which has stable electrical characteristics and is excellent in mass production by eliminating the above-mentioned conventional drawbacks. Structure of the Invention The present invention draws a thick film circuit by moving a drawing nozzle having a discharge hole at its tip for discharging thick film paste relative to a substrate while maintaining a distance between the discharge hole and the substrate. In this method, by using a plurality of drawing nozzles in which the distance between the discharge hole and the substrate is changed according to the width of the discharge hole, patterns with different line widths can be printed in a single film with a uniform thickness and without repetition. This is a drawing method for thick film circuits that can be formed by drawing. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described based on FIGS. 2, 3, and 4. Three types of drawing nozzles 1a, 1b, 1c with different widths l of the discharge holes 2 are installed in the nozzle switching section 12, fixed to the nozzle elevating section 11, and further connected via the Y-axis drive section 7 of the X-Y drive device. and is fixed to the X-axis drive section 13. In order to discharge the thick film paste 4, the drawing nozzles 1a, 1b, and 1c are pressurized by air pressure, and pressurization and depressurization are controlled by a solenoid valve 6. The substrate 5 is vacuum-adsorbed by a substrate fixing table 8 which can be moved up and down, and a solenoid coil 9 generates a pressing force to the drawing nozzle. Reference numeral 10 denotes a control device incorporating a microprocessor, which controls the switching of the drawing nozzles 1a, 1b, and 1c, the opening and closing of the electromagnetic valve 6, and the vertical movement of the substrate fixing table 8. The tips of the drawing nozzles 1a, 1b, and 1c have slit-shaped discharge holes (W=0.1 mm, l=1.0 mm or 2.0 mm or 30 mm) for discharging the thick film paste 4.
2 is provided, and a rectangular diamond chip 3 is bonded in front of the diamond chip 3 in the drawing direction. Now, in order to draw a thick film circuit on the substrate 5, select one of the drawing nozzles 1a, 1b, and 1c, lower it so that the diamond chip 3 touches the substrate 5, and then At least one of the shaft drive units 7 is operated to move the drawing nozzle. At this time, the electromagnetic valve 6 is opened at a preset timing and the inside of the drawing nozzle is pressurized with air pressure so that the thick film paste 4 is simultaneously discharged and the drawing circuit 14 is formed. Next, the electromagnetic valve 6 is closed to stop discharging the thick film paste 4, and at the same time, the drawing nozzle 1a, 1b, or 1c is raised to obtain a desired length. The pressing force of the substrate fixing table 8 against the diamond chip 3 is adjusted by the electric power applied to the solenoid coil 9, and is set to about 50 g in the embodiment. As a result of drawing using the following method, as shown in Table 2, even if the width l of the discharge hole 2 was changed, a constant film thickness could be obtained by changing the height h of the diamond chip 3. This is thought to be because the difference in the flow velocity of the paste between the center and the end of the discharge hole could be made uniform by changing h.

[Table] Here, within the scope of this example, the width l and height h of the ejection port have a roughly inverse correlation, but in order to obtain an appropriate film thickness t, h should be in the range of 10 to 80 μm. is preferable; if it is less than 10 μm, the film thickness will be too thin, or
If it is larger than 80 μm, the film thickness becomes too thick, and in either case, desired electrical characteristics such as resistance value cannot be obtained. In the embodiment, a drawing nozzle with a slit-shaped discharge hole is used, but the discharge hole may be circular, oval, or the like. Further, although a method of stabilizing the distance between the substrate and the discharge hole by a diamond chip contact method was used, the above-mentioned measurement method may also be used. Effects of the Invention As described above, according to the present invention, by using a plurality of drawing nozzles each having an appropriate distance between the substrate and the ejection hole and having different widths of ejection holes, drawing circuits having different line widths can be uniformly drawn. It has the excellent effect of being able to form a film with a certain thickness and at high speed with a single drawing without repeating the drawing, and has great industrial value in terms of stabilizing electrical characteristics and improving mass productivity.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a typical drawing method, Fig. 2 is a perspective view thereof, Fig. 3 is a system diagram showing an embodiment of the present invention, and Fig. 4 is a drawing nozzle in an embodiment of the present invention. FIG. 1... Drawing nozzle, 2... Discharge hole, 3... Diamond chip, 4... Thick film paste, 5... Substrate, 6... Solenoid valve, 7... Y-axis drive unit, 8... Substrate fixing stand , 9... Solenoid coil, 10... Control device, 11... Nozzle elevating section, 12... Nozzle switching section, 13... X-axis drive section, 14... Drawing circuit.

Claims (1)

[Claims] 1. Draw a thick film circuit by moving a drawing nozzle having a discharge hole at its tip for discharging thick film paste relative to a substrate while maintaining a distance between the discharge hole and the substrate. A method for drawing a thick film circuit, the method comprising: applying a thick film paste to a surface of a substrate using a plurality of drawing nozzles in which the distance between the ejection hole and the substrate is changed depending on the width of the ejection hole. 2. The method for drawing a thick film circuit according to claim 1, wherein the distance between the ejection hole and the substrate is narrowed as the width of the ejection hole becomes wider. 3 Equipped with multiple drawing nozzles in the nozzle switching section,
A method for drawing a thick film circuit according to claim 1, wherein a drawing nozzle to be used at a predetermined drawing position is automatically selected for drawing.